10-43
(for which careful cleaning and polishing of the glassy carbon electrode surface is
required between experiments).
The above method is called Anodic Stripping Voltammetry (ASV) since the stripping
current is anodic. This method can be used for metal ions that can be readily reduced
to the metallic state and reoxidized, which includes about 20 metal ions (e.g., Pb, Cu,
Zn, Cd). This is not as many as can be detected using Atomic Absorption
Spectroscopy (AAS), although the sensitivity of ASV is comparable with, and
sometimes better than AAS. The advantage of ASV over AAS is its ability to detect
several metal ions simultaneously (up to 6, depending on the stripping potentials of
the metals present). In addition, different oxidation states of one particular metal can
be detected.
Other stripping techniques include Cathodic Stripping Voltammetry (CSV) and
Adsorptive Stripping Voltammetry (AdSV). The basis for CSV is the oxidation of
mercury followed by the formation of an insoluble film of HgL (L is the analyte) on
the surface of the mercury electrode during the deposition step. This film is then
removed in the stripping step using a cathodic scan. CSV is most commonly used for
the detection of sulfur-containing molecules (e.g., thiols, thioureas and thioamides),
but it has also been used for molecule such as riboflavin and nucleic acid bases (e.g.,
adenine and cytosine).
AdSV is different from ASV and CSV in that the preconcentration step is non-
electrolytic, and occurs via the adsorption of molecules on the surface of the working
electrode (the mercury drop is most commonly used). The stripping step can be either
cathodic or anodic. AdSV has been used for organic molecule (e.g., dopamine,
chlorpromazine, erythromycin, dibutone, ametryne) and for metal complexes (e.g.,
dimethylglyoxime complexes of cobalt and nickel); hence, AdSV can be used for
detection of metal ions that are not suitable for ASV.
References
1 Stripping Voltammetry, A.W. Bott, Curr. Seps. 12 (1993) 141.
2 BAS Capsule No. 150 Anodic Stripping Voltammetry of Lead and
Cadmium
3 An Inexpensive Approach to Inorganic Gunshot Residue Analysis using
Anodic Stripping Voltammetry. S. Chouchoiy and R.C. Briner, Current
Separations 4 (1982) 20
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